The present invention relates to an image forming method, and in particular, to a method to form an image from an ink ribbon through thermal transfer.
Since images obtained through photographing by a digital camera can easily be processed on a personal computer, for example, it has become popular that a composite photograph, obtained by a user through addition of arbitrary characters or symbols, is outputted by an ink jet printer or a thermal transfer printer.
On the other hand, high quality images are formed by conventional silver halide photography, and they are used together with digital prints accordingly. Further, there has been developed a technology to form a digital image on a silver halide photograph.
Incidentally, as a prior art to compound characters with images on a silver halide photograph, there is known a technology, for example, wherein images from a negative film and characters are compounded by using a transmission-type original prepared by a computerized photo-typesetting machine. In this technology, however, it is not possible to form characters in a metallic color. If it was possible to form characters by the use of a metallic color on a silver halide photograph, beautiful hybrid images would be obtained from quality images and characters.
To meet this demand, there has been developed a technology to add characters to a silver halide photograph through melt thermal transfer from an ink ribbon (TOKKAIHEI No. 9-292686). This technology makes it possible, for example, to add arbitrary comments in a metallic color, to a silver halide photograph on which an image of a subject is formed.
However, there is a problem which is peculiar to the occasion of forming metallic color images in the technology. For example, when an image is smaller than the width of the ink ribbon, an evaporation layer on the ink ribbon corresponding to that image can be transferred collectively onto a silver halide photograph through melt thermal transfer, which makes it possible to form a flat image that is beautiful like the surface of a polished metal.
On the other hand, when an image is larger than the width of the ink ribbon, an evaporation layer on the ink ribbon corresponding to that image can not be transferred collectively onto a silver halide photograph through melt thermal transfer, which makes it necessary to split the image to be smaller than the ink ribbon width to transfer the image. However, when splicing the split images, there is caused a small step on the spliced portion. This step is as small as about 1 .mu.m and is hardly sensed when touched, but it is seen as a clear line when the metallic color image is reflected. The line formed on the metallic color image which looks like the surface of the polished metal may deteriorates quality of the image.
On the contrary, when the width of the ink ribbon is made to be larger than the size of the photograph, it seems to be possible to transfer an image to be transferred totally and collectively, and thereby to eliminate the spliced portion on the image. However, an image requiring a total ink ribbon hardly exists, and most images are considered to require only a part of the ink ribbon, which makes ink ribbons to be wasted exceedingly to increase cost of an image. When the width of the ink ribbon is made to be large, on the other hand, there is caused the problem that the thermal head needs to be greater, and the size and cost of a printer are also increased. In addition, there sometimes is an occasion where an ink ribbon needs to be used sparingly.